Subject Re: [IBO] New behaviour of OnDataChange-Event
After some testing I found out, that the OnDataChange-Event doesn't fire only, when
KeyDescLinks is not empty.
Any ideas ?


guido.klapperich@... wrote:

> > Not sure what would have caused this.
> > Not sure what could reverse it either.
> > Perhaps you could give more details.
> > There is probably a better way to do what you are doing.
> >
> I have a query ACQuery with 'select ACATID,.... from activities', ACATID is a
> FK. ACATID can be changed with a Lookup-Query , which is linked to a
> LookupCombo. In the OnDataChange-Event of the DataSource of ACQuery I ask
> if Assigned(Field) then
> if Field.FieldName='ACATID' then
> do something
> In the older versions of IBO this worked fine, but now (IBO 4.2 Fr) the
> OnDataChange-Event doesn't fire, when I change ACATID. I looked in the
> Release-Notes and I found this at release 4.2Fn:
> I made it so that the OnDataChange events when doing column modifications would
> distinguish between a direct assignment and an Assign() initiated assignment. I
> made it so that when directly assigning a new value it would always announce a
> datachange notification, whether or not the data value was actually changed.
> Only the Assign() will suppress announcement of an OnDataChange notification
> when the values are the same. This is important to have since the master-detail
> linking relies upon it reaching a point that there are no longer any binary
> differences between the linking columns. If there were differences or perpetual
> announcement of data change events there would be an infinite looping, as was
> the case in recent sub-releases where trying to keep the link between master and
> detail perfectly accurate when using callbacks. Keep in mind, callbacks are off
> by default for TDataset based stuff so this was only an issue to those using
> callback support, which is a nice luxury now ready for the prime time in the
> native IBO components and controls. I'd still be hesitant to turn them on in
> TDataset based components.
> Is this the reason for the new behaviour ?
> Guido
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